Leopold Mozart's "Violinschule" of 1756. Chapter II, Figures 4 & 5
Detailed instruction on bow hold. "The bow is taken in the right hand, at its lowest extremity, between the thumb and the middle joint of the index-finger, or even a little behind it. Observe the illustration, Fig. IV. ... but the stretching out of the index-finger is at all times a serious error [Fig V]".